Description

I have seen one situation with Hbase cluster.

Scenario is as follows:

1)1.5 blocks has been written and synced.

2)Suddenly cluster has been restarted.

Reader opened the file and trying to get the length., By this time partial block contained DNs are not reported to NN. So, locations for this partial block would be 0. In this case, DFSInputStream assumes that, 1 block size as final size.

But reader also assuming that, 1 block size is the final length and setting his end marker. Finally reader ending up reading only partial data. Due to this, HMaster could not replay the complete edits.

Actually this happend with 20 version. Looking at the code, same should present in trunk as well.

int replicaNotFoundCount = locatedblock.getLocations().length;
for(DatanodeInfo datanode : locatedblock.getLocations()) {
..........
..........
// Namenode told us about these locations, but none know about the replica
// means that we hit the race between pipeline creation start and end.
// we require all 3 because some other exception could have happened
// on a DN that has it. we want to report that error
if (replicaNotFoundCount == 0) {
return 0;
}